Vitamin E Helps Plasma Membrane Repair

AUGUSTA, Ga.Scientists from Georgia Health Sciences University have discovered what they say is the primary function of vitamin E in the body: helping to repair plasma membrane injury and controlling what enters and exits the cells. The results of the series of in vitro experiments were reported Dec. 20 in Nature Communications journal.

Cells such as cariomyocytes and skeletal muscle myocytes suffer physical disruption injury from mechanical stress in certain health conditions including severe vitamin E deficiency. Supplementing with vitamin E has been known to improve muscle health, but the underlying mechanism was not known.  The researchers considered the two prevailing theories whereby vitamin E acts a membrane stabilizer and/or it acts as an antioxidant. Cultured skeletal muscle cells soaked in -tocopherol showed enhanced membrane repair but not protection from damage. Results were similar for the same experiment in HeLa cell (the oldest human cell line used for in vitro research). Further tests indicated dosage and duraiton of exposure were critical factors in maximizing the health benefits.

As a part of the experiments, researchers also loaded repair-deficient cells (cultured in elevated glucose for 14 weeks) with -tocopherol, to see if vitamin E treatment could reverse a repair defect associated with diabetes. Vitamin E partially eliminated this defect. In other tests, vitamin E improved membrane repair in both skeletal muscle and HeLa cells and promoted long-term survival after mechanically induced disruption.

Using Trolox, which is the same as -tocopherol but without the hydrophobic tail, in similar experiments the researchers found both water and oil soluble version of vitamin E can support membrane repair, suggesting the key may be antioxidant properties. They further tested this conclusion by introducing an oxidant challenge to the design, which proved to have little effect on cell leakiness, but greatly inhibited repair. Pre-treatment of the cells with either tocopherols or Trolox preserved repair in the presence of the oxidant challenge, confirming the antioxidant properties of vitamin E are key to preserving membrane repair. However, subsequent testing with other antioxidants revealed antioxidant actions alone are not enough.

Lead researcher Paul McNeil, Ph.D., Georgia Health Sciences University, said  we consume enough vitamin E without any special effort, but until now researchers had no idea what its primary function in the human body was. We don't even know what it does in our bodies, he said, adding he now feels confident about at least one of its functions.